The present invention relates to an objective lens actuator for driving an objective lens for focusing recording/reproducing light onto a recording surface of an optical disc within an optical disc apparatus, and further it relates to, in particular, an optical pickup and an optical disc apparatus comprising the same objective lens actuator therein.
An optical disc apparatus, for recording information on a disc-like recording medium or reading the information recorded thereon, is able to record a relatively large amount or volume of information on a disc, and the medium is large in the rigidity thereof, so as to be handled easily; therefore, it is used widely, such as, an external recording device for a computer or a recording apparatus for video/audio, for example.
In such optical disc apparatus, the objective lens actuator is an apparatus for driving the objective lens for focusing lights upon the recording surface on the optical disc into a focusing direction (i.e., the direction of approaching/receding to/from the optical disc surface) and a tracking direction (i.e., the radius direction of the disc). In the following Patent Document 1, there is disclosed the objective lens actuator within the conventional optical disc apparatus.
As it is shown in FIG. 1 and so on of the Patent Document 1, in general, the objective lens actuator is constructed with a moving part, including the objective lens therein, a supporting member for supporting this moving part thereon, and a magnetic circuit made up with a yoke and permanent magnets. On the moving part are attached a focusing coil and a tracking coil, and with supplying drive current through the focusing coil, the moving part is driven into the focusing direction with electro-magnetic forces, which are generated due to actions between the magnetic flux from the permanent magnets, and also in a similar manner, with supplying drive current through the tracking coil, the moving part is driven into the tracking direction with electro-magnetic forces, which are generated due to actions between the magnetic flux from the permanent magnets.    [Patent Document 1] Japanese Patent Laying-Open No. Hei 11-316962 (1999), (see, page 5 and FIG. 1).